Galactokinase deficiency, an inherited defect, is a recognized cause of human cataracts. The biochemical processes involved are known, but the underlying genetic defect, i.e. regulatory or structural geen mutation is unknown. The purpose of this project is to purify human galactokinase enzyme. The purified enzyme will then be used to raise antisera for the purpose of screening a Lamba gt 11 human liver library. A partial amino acid sequence of the purified enzyme will also be generated to make an oligonucleotide probe for screening a human library. Both approaches will allow for the cloning of the human gene but do require a purified enzyme in sufficient quantity. Galactokinase will be purified from human placenta and/or red blood cells using an HPLC system, specifically Pharmacia FPLC. Homogeneity will be determined by SDS-polyacrylamide gel electrophoresis. The results of this project will serve as a foundation for an RO1 pertaining to the characterization of the human galactokinase gene.